Bonding pin



March 26, 1929. L, AYER 1,706,992

BONDING PIN Filed Feb. 26, 19215 013.663 67; @Z WQW 82% Patented Mar. 26, 1929.

U ITED STATES LOUIS H. AYER, OF CHICAGO, ILLINOIS.

BONDING PIN.

Application filed February 26, 1923. Serial No. 621,154.

My invention relates to bonding pins such as are used for attaching electrical conductors to rails, and has reference particularly to a bonding pin whereby a number of electrical conductors may be sin'iultanemisly secured to the rail by means of the same pin.

Tapered bonding pins are commonly employed for connecting electricz-rl conductors to rails, such pins being formed with one or more longitudinal grooves in which the con: doctor is clamped by wedging engagement of the pin in an aperture of the rail. These pins are usually circular in cross section so that a substantially uniform compressing straln is imposed on the pin as it is driven into the aperture of the rail, and in order to hold the conductor firmly in the groove, it is cnsto1 n ary to form the latter so that a SUlDStZLlltlzll portion of the conductor is exposed for direct wedging engagement with the aperture of the rail. This, however, results in a considerable mutilation or stripping back of the conductor which is of a comparatively soft material and not only reduces the conducting capacity but also increases the liability of breakage.

The principal objects of my invention are to provide a multiple groove bonding pin wherein. excessive stripping back or mutilation of the coinluctorsis avoided; to localize the compressing strain on the pin so that it is etlective at opposite sides or? each groove and tends to close the portions of the bonding pin at each side of the groove over the exposed portion of the conductor; and in general, to provide an improveifi bonding pin for securing a number of conductors silnul 'taneously to a rail.

On the drawings: Fig.

groove bonding pin constructed in accordance with inyinvention;

Fig 2 a view looking at the smaller end of the bonding pin shown in Fig. 1;

Fig. 3 a view partly .in section showing the manner of connecting rails with my in1- proved bonding pin;

Fig. 4- an enlarged view on the line 55 of Fig. 3, showing the bondii'lg pin in position n'eparatory to being driven into the rail aperture Fig. 5 a similar view showing the bonding pin driven into place Fig. 6 an enlarg d. seetional view on the line a i i a? receive the 1 is an enlarged side view of a double from the grooves angles to the and-plane A-A. so that maxr Fig. 7 a view similar to Fig. 2 showing my invention embodied in a bonding pin having three Wire grooves; and

Fig. 8 a similar view showing the bonding pin provided with four wire grooves.

Referring to the drawings, the numerals 1-1indicate two adjoining rails, 2-2 condoctors for connecting the two rails and 33 apertures in the rails in which the ends of he conductors 2 are to be secured. The bond :ing pin is indicated as a whole at 4- and is tapered at one end asindioated at 5, to facilitate insertion in the aperture 2) of the rail. A pair of grooves 66extend from end to end of the pin. and at opposite sides thereof to coin'luctors 2, and the portion 7 of the pin beyondthe tapered portion 5 is also tapered but more gradually than the portion 5, in order to afford a driving fit in the aperture 3, whereby the pin is not only secured in the aperturebut also caused to clamp the conductors 2 in the grooves 6.

The taper of the portion 5 of the pin may be of ordinary conical formation, that is, of such a form that all sections thereof are circular in form, but the portion 7 is of a special tapered form to etl'ect a more substantial clam 'iing or gripping of the conductors 2 in the grooves 6 and also to avoid unneccs sary mutilation of the wire. To this end the portion 7 is not tapered in the midplane A i r of the grooves 6 but is of a uniform thickness,substantially the same or a trifle greater than the diameter of the rail aperture 3 in which it is to be inserted, but the pin is of oval or elliptical cros section and tapered in the plane 13 -13 at right angles to the midplane of the grooves 6, the portions at opposite sides of the plane A-A being forn'led about divergent axes so that the portion 7 is not onl i formed with a radual longitudinal taper but the taper thereof increases with the cn'cumferential distance 6-6 to points at right mum taper is in theplane B B.

With this construction there is practically no wedge action on the pin in the plane A-A of the grooves 6 but merely a snug fit, the grooves 6 being parallel and uniformly spaced from the plane BB so that the con doctors 2 when seated in the grooves 6 are substantially parallel. The grooves 6 are also at such depth that only a small portion of the conductors 2 are exposed for engagement with the rail aperture, such engagement being provided to afford a scraping acductors avoided.

\Vi th the construction described, when the conductors are laid in the grooves 6 and the pin driven into the ra l aperture 3, the compressing strain of the wedgev engagement is exerted in a direction crosswise of the grooves 6 and only a snug fit occurs between the pin andthe conductors and rail aperture in the mid-plane AA of the grooves, thereby affording relief for the compressing strain in circumferential directions at each side of the 7 plane BB of maximum compressing strain.

This results in a slight crowding of the oppositegrooved sides of the pin against the corresponding opposite sides of the aperture 2 sufiicient to hold the conductors 3 firmly against the rail aperture and also causes the lips or outer extremities of the side walls of the grooves to fold over the exposed portions of the'conductors 3 substantially as shown in Fig. 5, so that the conductors are clamped down in the grooves 6 and firmly engaged at all points therearound by the pin 4 excepting at the portions of their surfaces where contact is had between their conductors and the rail.

A perfect electrical connection is thus afforded as well as a substantial mechanical 7 connection without the excessive mutilation 011 peelingback of the conductors which occurred in previous bonding pin structures, and, moreover, the capacity of the conductor is practically unimpaired and liability-0f breakage reduced to a minimum.

In Figs. 7 and .8 I have. shown modified forms of bondingpins constructed in accord- "ance with the invention just described but arranged with three. and four grooves respectively for connecting 'a corresponding tapered excepting between the grooves. To

this end the portions between the grooves are formed on divergent axes so that said portions are characterized by an arcuate bulge which gradually increases from end to end of the pin, and this afiords a maximum compressing strain midway between the grooves as in the structure of Figs. 1 to (i inclusive, and results in the folding of the side lips of the grooves over the conductors so that the conductors are securely clamped in the bonding pin, the latter locked in the rail aperture and suificient contact permitted between the conductors and the rail aperture to afford the proper electrical connection.

\Vhile I have shown and described my invention in a preferred form. .1: am aware that various changes and modifications may be made without departing from the principles of my invention, the Scope of which is to be determined by the appended claims.

I claim as my invention: I

1. An electrical connector comprising a pm having a plurality of longitudinal grooves, said pin being of the same radius throughout the major portion of its length on the planes bisecting the respective grooves on the grooved side of the pin and being provided with a circumferential bulge between the grooves and extending lengthwise of the pin, said bulge having the axis thereof divergently arranged with respect to the longil udinal axis of the pin.

2. An electrical connector consisting of a pin having a plurality of parallel longitudinally extending grooves, said pin being of uniform diameter a major portion of its length on the planes bisecting the grooves on the grooved side of the pin and provided with an arcuate enlargement between the grooves extending lengthwise thereof, said enlargement being formed aboutan axis which is diver-gently arranged relatively to the longitudinal axis of the pin.

3. An electrical connector consisting of a pin having a plurality of longitudimil grooves, said pin being untapered in the midplane of each groove on the grooved side of the pin and having a tapered form gradually increasing from each groove to a point mid way between it and the adjoining groove or grooves.

4. An electrical connector comprising a pin having a plurality of longitudinal grooves, the diameter of said pin at any point in a major portion of its length and on any of the planes bisecting the respective grooves being the same on the grooved side of the pin, and said pin being of increasing diameter from end to end of such major portion in planes passing through portions of the pin located between the grooves thereby centering all compressing strain, when the pin is driven, between the grooves.

5. An electrical connector comprising a pin having a plurality of longitudinal grooves, the radial dimension of said pin at any point in a major portion of its length and on any of the planes bisecting the respective grooves being the same on the grooved side of the pin, and said pin being of increasing radial dimension from end to end of such major portion in planes passing in the portions of the pin located between the grooves thereby centering all compressing strain, when the pin is driven at a plurality of spaced points on the periphery of the pin between the grooves.

An electrical connector comprising a pin having a plurality of longitudinal grooves, the radial dimension of said pin at any point in a major portion of its length and on any of the planes bisecting the respective grooves being the same on the grooved side of the pin, and said pin being of increasing radial dimension from end to end of such nlaj or portion in planes passing in the portions of the pin lOCt ted between the grooves thereby centering all compressing strain, when the pin is driven, between the grooves at a plurality of spaced points on the periphery of the pin.

7. A bonding pin formed with three or more grooves therein for the wires the dian1- eters of the pin being constant through a major portion of the length of the pin :trom endto end when taken on planes bisecting the grooves on the grooved side of the pin, and

gradually increasing on planes passing between the grooves.

8. A bonding pin having a plurality of longitudinal grooves of a depth less than a radius at any point, said pin having a tapered entrance end and tapering to a less degree between said end and the head at a plurality of longitudinal points between the grooves and gradually increasing in taper circumferentially from the side of each groove to a point midway between a pair of grooves, the portions of the pin between the sides of the grooves beyond the tapered entrance end and in planes bisecting said grooves being untapered and continuously uniformly spaced from the axis of the pin along the lengths of the grooves, whereby opposite sides of the pin at each groove are compressed around a cond uctor inserted therein when the pin is driven into a rail aperture, in conformity with the surface of the conductor, whereby peeling or shearing of the conductor at the edge of the rail aperture is prevented.

LGUIS H. AYEI-t. 

